1. Field of the Invention
The present invention relates to an alternating-current (AC) conversion system; in particular, to an AC conversion system having a low power consumption bleeder circuit.
2. Description of Related Art
The power system used in the household appliances or the information products usually includes a power converter for providing various kinds of power voltages required by the products. The input of the power converter is generally provided by the main alternating-current (AC) power source. After passing through an electromagnetic interference (EMI) filtering circuit, designed to include inductors and the capacitors, and rectifier, the main AC power voltage is converted to the demanded power voltages, such as direct-current (DC) voltage 19V or 5V, etc. However, when the AC power source is removed and does not provide power supply, the electric power may still be stored in the inner capacitors. For ensuring safety, the general safety voltage specification restricts that the voltage of the inner capacitor should be reduced to lower than 37% of the original value within one second. Thus, a bleeder component is installed within the circuits for bleeding the electric power stored in the inner capacitors. Conventionally, a resistor may be disposed between the two input terminals of the electric power for serving as the bleeder component. However, under normal power supply, the resistor may consume power corresponding to the value of the power voltage, and the total power consumptions thereof are hard to comply with the low power consumption standard.